Dataset Information

Oenococcus oeni in Chilean Red Wines: Technological and Genomic Characterization.

ABSTRACT: The presence and load of species of LAB at the end of the malolactic fermentation (MLF) were investigated in 16 wineries from the different Chilean valleys (Limarí, Casablanca, Maipo, Rapel, and Maule Valleys) during 2012 and 2013, using PCR-RFLP and qPCR. Oenococcus oeni was observed in 80% of the samples collected. Dominance of O. oeni was reflected in the bacterial load (O. oeni/total bacteria) measured by qPCR, corresponding to >85% in most of the samples. A total of 178 LAB isolates were identified after sequencing molecular markers, 95 of them corresponded to O. oeni. Further genetic analyses were performed using MLST (7 genes) including 10 commercial strains; the results indicated that commercial strains were grouped together, while autochthonous strains distributed among different genetic clusters. To pre-select some autochthonous O. oeni, these isolates were also characterized based on technological tests such as ethanol tolerance (12 and 15%), SO2 resistance (0 and 80 mg l-1), and pH (3.1 and 3.6) and malic acid transformation (1.5 and 4 g l-1). For comparison purposes, commercial strain VP41 was also tested. Based on their technological performance, only 3 isolates were selected for further examination (genome analysis) and they were able to reduce malic acid concentration, to grow at low pH 3.1, 15% ethanol and 80 mg l-1 SO2. The genome analyses of three selected isolates were examined and compared to PSU-1 and VP41 strains to study their potential contribution to the organoleptic properties of the final product. The presence and homology of genes potentially related to aromatic profile were compared among those strains. The results indicated high conservation of malolactic enzyme (>99%) and the absence of some genes related to odor such as phenolic acid decarboxylase, in autochthonous strains. Genomic analysis also revealed that these strains shared 470 genes with VP41 and PSU-1 and that autochthonous strains harbor an interesting number of unique genes (>21). Altogether these results reveal the presence of local strains distinguishable from commercial strains at the genetic/genomic level and also having genomic traits that enforce their potential use as starter cultures.

SUBMITTER: Romero J

PROVIDER: S-EPMC5817079 | biostudies-literature | 2018

REPOSITORIES: biostudies-literature

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Oenococcus oeni in Chilean Red Wines: Technological and Genomic Characterization.

Romero Jaime J Ilabaca Carolina C Ruiz Mauricio M Jara Carla C

Frontiers in microbiology 20180214

The presence and load of species of LAB at the end of the malolactic fermentation (MLF) were investigated in 16 wineries from the different Chilean valleys (Limarí, Casablanca, Maipo, Rapel, and Maule Valleys) during 2012 and 2013, using PCR-RFLP and qPCR. Oenococcus oeni was observed in 80% of the samples collected. Dominance of O. oeni was reflected in the bacterial load (O. oeni/total bacteria) measured by qPCR, corresponding to >85% in most of the samples. A total of 178 ...[more]

PMID: 29491847

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Project description:Oenococcus oeni is the lactic acid bacterium (LAB) that most commonly drives malolactic fermentation in wine. Although oenococcal prophages are highly prevalent, their implications on bacterial fitness have remained unexplored and more research is required in this field. An important step toward achieving this goal is the ability to produce isogenic pairs of strains that differ only by the lysogenic presence of a given prophage, allowing further comparisons of different phenotypic traits. A novel protocol for the rapid isolation of lysogens is presented. Bacteria were first picked from the center of turbid plaques produced by temperate oenophages on a sensitive nonlysogenic host. When streaked onto an agar medium containing red grape juice (RGJ), cells segregated into white and red colonies. PCR amplifications with phage-specific primers demonstrated that only lysogens underwent white-red morphotypic switching. The method proved successful for various oenophages irrespective of their genomic content and attachment site used for site-specific recombination in the bacterial chromosome. The color switch was also observed when a sensitive nonlysogenic strain was infected with an exogenously provided lytic phage, suggesting that intracolonial lysis triggers the change. Last, lysogens also produced red colonies on white grape juice agar supplemented with polyphenolic compounds. We posit that spontaneous prophage excision produces cell lysis events in lysogenic colonies growing on RGJ agar, which, in turn, foster interactions between lysed materials and polyphenolic compounds to yield colonies easily distinguishable by their red color. Furthermore, the technique was used successfully with other species of LAB.IMPORTANCE The presence of white and red colonies on red grape juice (RGJ) agar during enumeration of Oenococcus oeni in wine samples is frequently observed by stakeholders in the wine industry. Our study brings an explanation for this intriguing phenomenon and establishes a link between the white-red color switch and the lysogenic state of O. oeni It also provides a simple and inexpensive method to distinguish between lysogenic and nonlysogenic derivatives in O. oeni with a minimum of expended time and effort. Noteworthy, the protocol could be adapted to two other species of LAB, namely, Leuconostoc citreum and Lactobacillus plantarum It could be an effective tool to provide genetic, ecological, and functional insights into lysogeny and aid in improving biotechnological processes involving members of the lactic acid bacterium (LAB) family.

Dataset Information

Oenococcus oeni in Chilean Red Wines: Technological and Genomic Characterization.

Publications

<i>Oenococcus oeni</i> in Chilean Red Wines: Technological and Genomic Characterization.

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